I've learnt quite a bit. Enough to change my opinions on some topics. Or at least have a more nuanced approach. The level of sourness being a big one. You'll need to buy the book if you want to learn all the details.
In the meantime, here's a description of the brewing process at one Berlin brewery between the was.
In the kettle, the malt was doughed in with water at 30º C. The temperature was slowly raised to 53º-54º C where it was held for 30 minutes for a protein rest.
The temperature was raised to 75º C by which time saccharification should have occurred.
A third of the wort was transferred to the lauter tun and the remainder of the wort in the kettle brought to the boil.
After boiling for 30 minutes, it was mixed with the other third of the wort in the lauter tun, making sure the temperature didn’t exceed 76º C. The mixture was left to stand for 40 minutes before running off.
The clear wort was returned to the kettle and brought to 95º C for 15 to 20 minutes. Then immediately cooled to 18º C.
The wort was pitched at 16º C and after four days the temperature rose to 20º C. When it had dropped back down to 16º C, primary fermentation was done.
1º to 1.25º Plato gravity needed to be left for bottle conditioning. If not, Frischbier needed to be added to raise the gravity to the required level.
"Die Herstellung obergärige Biere und die Malzbierbrauerei Groterjan A.G. in Berlin" by A. Dörfel, 1947 pages 12 - 14.